How to burn MP3 files?

In brasero, you should be able to select new audio project, then drag and drop files.

Of course you'll probably notice the files I'm using in this example are .ogg.
That's just another format for multimedia files. You'll want to drag .mp3 files since it sounds like you want them to play on a device that supports mp3.

If your CD player can play MP3 CDs, you can create a Data Project in Brasero and copy your MP3s onto the CD as regular files. This allows you to fit 100--200 songs on a CD depending on their quality.

BUT, different players have different limitations on things like filenames, limits of subdirectories, etc. so it may take some experimenting to figure out what your MP3 CD player can and cannot play.

Otherwise, if your CD player does not support MP3s, you're stuck with regular audio CDs (80 minutes).

Just use Asunder. sudo apt-get install asunder. It works out of the box with fixed (up to 320 kbps) and variable bitrates. Though, I did have to go to preferences and change the CD-ROM device to /dev/sr0.

In the past I have burnt many mp3 files with K3b to data disc and played them in a car cd/mp3 player. I always burnt these mp3 files to a data disc however recently I tried to do it again and had unplayable discs. i realised that the file format was incorrect and had success when i Changed the format from Linux/unix +windows to Custom - Rock ridge/joliet format.This can be selected after clicking the burn button and clicking on filesystem, then scroll down to "Custom ( Rock ridge / joliet )selecting that item. Then after burning them as data discs they will playable on a CD/mp3 player. I like to use easytag prior to burning mp3s so that these tags show on player screen as artist and track